The mechanism for glutamine utilization by various glutamine amidotransferase including anthranilate synthetase is under examination. Affinity labeling of the glutamine site of amidotransferases using 2- amino-4-oxo-5-chloro(5-14C)pentanoic acid will allow detection and isolation of the tryptic peptide containing the glutamine binding site. This tryptic peptide from various types of anthranilate synthetase and other glutamine amidotransferases will be sequenced to help evaluate the proposal of evolution from a common ancestral gene. An immunochemical investigation of effect of ligands on enzyme conformation and submit association as well as relatedness among various anthranilate synthetase enzymes and other amidotransferases will be conducted.